@oralloy,
1. What I see is Max asserting a false misleading narrative.
2. Oralloy, I don't put too much into labels.
3. Whatever label you choose to use is up to you.
4. I don't know of any liberals or progressives that are making the argument that the British Empire is not responsible for slavery.
5. That sounds like Max is trying to push a narrative.
6. The following is an insert I copied from Wikipedia.
7. Being that I've been out of school for a very long time, I have forgotten much of what I learned in school.
8. As far as I can remember, the information contained in Wikipedia is essentially what I was taught in school many many years ago.
9. I am not going to remember dates, years, and many of the details.
10. By the way, I am a liberal or if you prefer, progressive.
Wikipedia
Slavery in the United States was the legal institution of human chattel slavery, comprising the enslavement primarily of Africans and African Americans, that existed in the United States of America from its founding in 1776 until the passage of the Thirteenth Amendment in 1865.
Slavery was established throughout European colonization in the Americas. From early colonial days, it was practiced in
Britain's colonies, including the Thirteen Colonies which formed the United States. Under the law, an enslaved person was treated as property and could be bought, sold, or given away. Slavery lasted in about half of U.S. states until 1865. As an economic system, slavery was largely replaced by sharecropping and convict leasing.
https://en.wikipedia.org/wiki/Slavery_in_the_United_States